Engine for delivering compressed air and power



Nov. 17, 1931; s ow 1,831,976

ENGINE FOR DELIVERING COMPRESSED AIR AND POWER Filed July 11, 1929 lI/IIII/IIIII/ I JIIIJII/l/l/I/l/l/l/ Hermes RoLFE STOW INVENTOR;

A}, Attorney ton,

Patented Nov. 17, 1931 UNITED STATES PATENT OFFICE GEORGE ROLFEI STOW, OF SENIOR PARK, SOUTH AUSTRALIA, A'USTRALIA ENGINE FOR DELIVERING COMPRESSED AIR AND POWER Application filed July 11 1929, Serial No. 377,365, and "ii! Australia July 28, 1928.

My invention relates to improvements in and connected with engines for obtaining compressed air and power. The engine hereinafter described, although in some respects similar in design to an internal combustion engine, must not be confused with that type a by the prime mover for delivering air for use outside the cylinder as for instance to an accumulator or to a pneumatically operated machine.

With my invention I am able to compress air on one side or on both sides of the pisbut whether one or both sides of the piston are used for compressing air I mount both a steam inlet and a compressed air outlet in the cylinder on the same side of the piston, or in other words I use one side of the piston both for power and compressing purposes by admitting steam when the piston is on the centre at the end of the stroke;

' cutting off steam at a predetermined point.-

allowing the steam to expand as is usual on an ordinary steam engine, exhausting the steam to atmosphere or to another engine near the end of the stroke. and according to design or adjustment simultaneously or 40 nearly simultaneously admitting the scavwhich expels the exhaust steam and fillsthe cyl nder with fresh air.

The momentum of the fly wheel carries the piston round the dead centre and causes the commencement of the up stroke whereby the scavenge opening or openings are closed, and durina the remainder of thestroke air wh ch has been admitted remains in the cylinder after the exhaust steam has been scavenged out and the exhaust opening has been enere air to the cylinder-above the pistonclosed. The air is compressed and expelled during the completion of the cycle, after which fresh steam enters the cylinder and repeats the above described series of operatrons. '65 It is of course essential in the design of :the machine that the setting of the steam valve be so arranged that the quantity of steam admitted will be suiticient to develop more power than will be required for com-' pressing the'air to the desired pressure and also for subsequently expelling the. air, and if so desired to additionally drive any 1nachinery which may be connected to the engine. i Obviously the adjustment and timing of the-valves will vary according to requirements and must be calculated according to the use to which the compressor is to be applied.

I willnow describe my invention as constructed and applied to an engine in which only one sideof the piston is used for the double purpose of compressing air and supplying power by aid of the accompanying drawings wherein Fig. 1 is a frontelevation of my device in part section.

Fig. 2 is a side elevation of Fig. 1 in part section;

Fig. 3 is a plan showing upper portion of Fig. 1. i

Figs; 4, 5'and 6 are sectional illustrations of valves suitable for use in my device. These valves present no feature of novelty. 9

In each of the illustrations similar letters of reference are used to denote similar or corresponding parts wherever they occur.

In thedrawines a is a cylinder fitted at its upper end with a cover a, the cylinder being adapted to rest upon a cylindrical portion '6' of a main casting or crank case 7).

Within the main casting I providev bearings a suitable for the support of the crank shaft and crank cl upon which a fly wheel (2 may be supported.

I also mount on the crank a. connecting rod 7 of any suitable design and a gudgeon pin 7" for a reciprocating piston g.

The piston g is operated by steam from some external source of supply which is admitted to the cylinder through a suitable steam intake or valve h. This valve may vary in design, but a suitable form is shown in Fig. 6 of the drawings.

This intake valve for the admission of the steam is preferably operated by a mechanical device such as hereinafter more fully described. The steam is admitted under pressure and acts expansively as in an ordinary steam engine and drives thepiston to its lowest position within the cylinder, the steam being cut oil at a predetermined point. The steam is exhausted to atmosphere or to another engine when nearing the end of the down stroke of the piston.

.An exhaust valve of suitable device is shown at 1' in Figs 1, 2 and 3, and also in Fig. 4 of the drawings, and when thepiston is approaching the position illustrated in Figs. 1 and 2 of the drawings s' avenge air is admitted to the cylinder immediately above the p ston.

This scavenge air is under aslight pressure and in the tyne of engine shown'in the illustrationsis obtained from the crank case through the outlet Z? from whence it asses through the pipe 71; and enters the cylinder above the piston through the. ports 702, a'very fine spray of water being simultaneously admitted through the pipe and spray nozzle 1. to keep down the temperature of the air thereby reducing the power which :is 'required tocompress it and fat the same time acting as a substitute for a water jacket. The scavenge air expels the exhaust steam through the exhaust valve j, the upward stroke of the piston closes the ports I 2 and 46 cuts oil the supply of scavenge air.

Simultaneously or almost simultaneously the valve j is closed.

When the exhaust outlet 7' is closed the upward return stroke of the piston continues so that the piston compresses the remaining air and forces it under compression through the air valve it until the cycle is completed. The expelled compressed air is delivered to its required destination and fresh steam enters the cylinder and commences another cycle.

The compression ofthe air heats the cylinder Walls and cover to'a temperature suitab e for the adm ssion of steam for each suceedins: stroke. thus adding to its efficiency by preventing initial condensation. and, moreover, the small quantity of air which remains in the cylinderat the end of the stroke mixes with the newly admitted steam and acts as a power immediately the piston has passed the dead centre.

It is to be distinctly understood that the momentum of the fly wheel carries the piston upwards and round the dead centre and it is therefore essential that in the design of the machine the setting of the steam valve should be so arranged that the quantity of steam admitted will be suflicient to develop more power than will be required for compressing the airto the desired pressure and also for subsequently expelling the air, and if so de sired the steam supply may be further increased to enable it to additionally drive any machinery which may be connected with the engine.

'Io supply the necessary air for scavenge purposes I fit an air valve 0 in the crank case, such valve being adapted to close under pressure, but to supply the crank case with air by suction whilst the pistonis travelling upwards. Such an arrangement is suitable to the design of engine shown in the accompanying drawings, but the air supply may be contributed by otherrmeans without departing from the nature and principle ofmy invention.

In order to operate the valve-h and "I use rods h and j which are mounted insuitable bearings. The valvesare provided at their upper ends with short operating spring governed guide stems b2 and i2. Levers p are designed to engage the valve stems and are fulcrumed on a support or bracket 9 and connected to therods h and j, the lower ends of which are designed .to be operated by cams which are timed to rotate in such a manner as will give effect to the above described cycle of movements.

For this purpose I may arrangea train of tooth wheels '2" which derive primary'motion from the mainshaft and transmit it to a cam shafts. Upon the cam shaft the cams t and t are supported and adjusted and transmit motion to rods 72 and j by means of the cams, one of the rods j may be direct acting and working upwards whilst the other h is fitted with a connecting bridle 713 and operatedby downward movement.

In the foregoing specification I have described a single acting compressor and engine but the principles herein disclosed may be applied so as to act on both sides of a piston of suitable design which is similarly accommodated within a suitable cylinder to which .any'known method of supplying scavenge airis used and of exhausting the contents of the cylinder is effected.

:In air compressors as at present in use loss tot 'efiiciency occurs through the compressed air which fills the clearancespaces and'conseq'uently hasto expand on the suction stroke of the piston to the pressure of the incoming air before the incoming air enters'the cylind'eigbut in my device a power stroke-not a suction strokefollows the compression stroke, and consequently the above indicated 1 losses are avoided.

A further economy is obtained in my device by the use of the water spray previously referred to, whereby water enters into the air in the torm ofiaim'ist which absorbs most of the heat of the compression so that the compressed air leaves the compressor at approximately the same temperature as saturated steam at that pressure. 7

Having now fully described and ascertained my said invention and the manner in which it is to be performed, I declare that what I claim is V 1. In a reciprocating engine, the combination of a piston, a cylinder therefor having a steam inlet port and a compressed air outlet port on the same side of the piston head, and a valve for each port coacting to alternately actuate the piston by steam on the initial stroke and to compress and expel the compressed air on the return stroke.

2. A reciprocating engine as claimed in claim 1, including an air pipe connected to the cylinder to admit air at loW pressure for scavenging exhaust steam above the piston at or near the end of the steam stroke.

3. A reciprocating engine as claimed in claim 1, including means for timing and controlling the valves for the admission of steam and the compression ofair to avoid the expansion of any compressed air which remains in the clearance space of the cylinder to the pressure of the incoming air.

In testimony whereof I alfix my signature.

GEORGE ROLFE STOW. 

